What size portable generator is needed to power a house?
Portable generators for homes typically range from 5kW to 20kW, depending on the appliances powered. Essential systems (fridge, lights, sump pump) require 3–5kW, while whole-house coverage (including HVAC) demands 10–20kW. Always calculate starting watts (surge) + running watts, adding 20% buffer. For example, a 7.5kW generator handles central AC (3.5kW) plus essentials. Consult an electrician for load calculations and transfer switch compatibility. Best Battery Backup System for Home Use in 2025
How do I calculate my home’s wattage requirements?
Start by listing essential appliances and their starting/running watts. Surge-prone devices like AC units or refrigerators need 2–3x their running wattage. Use a wattage calculator or clamp meter for accuracy. Pro Tip: Prioritize motor-driven appliances first—they dictate surge capacity needs.
To calculate your total wattage, add the starting watts of your largest appliance (e.g., central AC at 3,500W) to the running watts of all others. For a 1,500 sq ft home, essentials like a fridge (800W), lights (500W), and a well pump (1,000W) total ~5,300W. But since generators shouldn’t exceed 80% load, a 7kW unit is safer. Transitional note: Beyond basic math, consider fuel type—gasoline generators lose efficiency above 50% load. For example, a 10kW propane generator running at 7kW maintains stable voltage, whereas gasoline units may struggle.
| Appliance | Running Watts | Surge Watts |
|---|---|---|
| Central AC | 3,500 | 7,000 |
| Refrigerator | 800 | 2,200 |
| Sump Pump | 1,000 | 3,000 |
Portable vs. standby generators: Which is better for home use?
Portable generators (5–10kW) are affordable and mobile but require manual setup. Standby units (10–20kW) auto-start during outages but cost $4k+ installed. Choose based on outage frequency and budget.
Portable generators excel for infrequent outages under 12 hours. They’re fueled by gasoline or propane and must be operated outdoors due to carbon monoxide risks. Standby generators, however, connect to natural gas lines and power critical circuits automatically. Transitional note: Practically speaking, if you’re in a storm-prone area, standby units offer peace of mind. For example, a 16kW standby generator powers a 2,000 sq ft home with two AC zones, while a portable 9kW unit would struggle.
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| Feature | Portable | Standby |
|---|---|---|
| Cost | $600–$2,000 | $4,000–$15,000 |
| Installation | DIY | Professional |
| Runtime | 8–12 hrs | Unlimited |
What size generator is needed for essential appliances?
A 5–7kW generator powers essentials: fridge (800W), lights (500W), furnace (1,000W), and a microwave (1,000W). Add 20% buffer for surge loads, totaling 4.5–6kW.
Essential systems vary by household—medical equipment like CPAP machines add 200W, while sump pumps demand 1,500W surge. Transitional note: But what if you need to run multiple high-wattage devices simultaneously? A 7kW generator handles a fridge (800W), well pump (1,000W), and window AC (1,200W) but may trip if a hair dryer (1,500W) is added. For example, a Honda EU7000is provides 5,500 running watts, safely supporting most essentials.
Can inverter generators power entire homes?
Inverter generators (3–7kW) are quieter and fuel-efficient but lack the capacity for whole-house coverage. Pair multiple units via parallel kits for up to 10kW.
Inverters produce clean power (<3% THD) safe for electronics, unlike conventional generators. However, their smaller fuel tanks limit runtime. Transitional note: For a 2,000 sq ft home, two parallel 7kW inverters (14kW total) could run a 4-ton AC (6,000W) and kitchen appliances. But is this cost-effective? At $2,500 per unit, standby generators often offer better value. Rack Mount Battery
How does fuel type impact generator sizing?
Gasoline offers higher energy density but degrades quickly. Propane lasts indefinitely and burns cleaner, but generators lose ~15% power output.
A 20lb propane tank (4.7 gallons) provides 10–12 hours at 50% load on a 5kW generator. Dual-fuel models add flexibility but cost 20% more. Transitional note: What’s the trade-off? Propane’s lower energy density means you’ll need larger tanks for equivalent runtime. For example, a 6kW dual-fuel generator running on gasoline lasts 8 hours vs. 5.5 hours on propane.
What safety features are critical for home generators?
Automatic voltage regulation (AVR) prevents power spikes. CO detection and low-oil shutoff protect against accidents.
Generators must be placed 20+ feet from windows and hardwired via transfer switches to avoid backfeed. Transitional note: Ever heard of a generator melting your wiring? Undersized cords (<10AWG for 30A loads) overheat, causing fires. For example, a 7kW generator requires a 30A twist-lock outlet and 10-gauge extension cords.
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FAQs
Yes, if the AC’s starting watts are ≤6,300W (e.g., 3-ton unit). Confirm your compressor’s LRA rating—multiply by voltage for surge watts.
How long can a portable generator run continuously?
Most last 8–12 hours at 50% load. For multi-day outages, consider propane or dual-fuel models with larger tanks.
Do I need an electrician to install a generator?
Required for standby units and transfer switches. Portable generators only need DIY setup if using extension cords.
